1. Field of the Invention
This application concerns a thermal isolation device for placement between the liquid cooling system of a vehicle (engine, pump and radiator) and a heat exchanger (heater core) for the passenger compartment. Below a maximum desired liquid temperature, the isolation device allows liquid from the engine cooling system to flow to the heat exchanger and back into the engine cooling system. Above the maximum liquid temperature, a thermal power element and associated valves block flow to the heat exchanger and redirect flow in bypass relationship to the heat exchanger.
2. Description of Related Art
The subject thermal isolation device provides protection from thermal damage for a heater core such as the heater in a vehicle. Applicant is unaware of any other device for this purpose. However, from an operational standpoint, the nearest known device is the common automotive engine thermostat. This engine thermostat is typically located at the outlet of the engine cooling system. When in a closed operative condition, it prevents circulation of coolant through the radiator so that the engine more rapidly reaches an operating temperature. When the coolant temperature increases to a start-to-open temperature, a thermal power element in the thermostat begins to open a valve so that coolant is permitted to flow through a radiator and then back to the engine by means of a pump.
The subject thermal isolation device uses a thermal power element which is similar to the power element in the above described thermostat. In the isolation device, the power element opens a bypass valve and closes other valves so that the excessively hot liquid cannot flow into the heater which is provided to warm air in the passenger compartment. This protects the heater core from damage. In use, the isolation device is positioned between an engine cooling system including a radiator and the heater core.